Soft touch top cover and method of manufacturing

ABSTRACT

In this invention, a composite finishing cover for a component such as a vehicle instrument panel is provided by extruding a parison of inner and outer layers of different recyclable plastics having different characteristics but which are from the same family. The parison is injected with low pressure gas when forming dies are being closed thereover so that the plastics will fully conform to the forming surfaces of the die tooling cavity. The closing force of the dies cause the heat softened inner layers of the first plastics material to join at their interface to form a relatively thick core or substrate providing structural support for the relatively thin and flexible outer layer of the cover, also joined at their interface. The outer layer provides a finishing surface that exhibits a soft feel as when the human hand lightly contacts and moves across the surface thereof. Importantly, in this invention the finishing cover can be readily recycled as a unit without the necessity of separating the different plastics layers from one another since they are from the same family of plastics.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of application Ser. No. 08/521,764, filedAug. 31, 1996 by the same inventors as the present application nowabandoned.

BACKGROUND OF THE INVENTION

Prior to the present invention, finished covers for a wide variety ofproducts have been made from different plastic materials layered orotherwise combined by various processes into desired shapes andfinishes. For example, many modern vehicles have instrument panels withspecial top covers that provide different degrees of softness andtactile feel to meet the customer requirements. In general three majorprocesses and constructions are employed for such top covers as follows:(1) a "super soft" top cover made from a hard structural plasticsretainer as a substrate or base, an intermediate polyurethane foam, anda roto--cast or slush molded vinyl outer skin, (2) a "soft" top covergenerally comprised of a hard plastic retainer as a substrate and abi-laminate vinyl skin that utilizes an expanded vinyl foam orpolyurethane foam on the underside of the skin, and (3) a "soft touch"top cover that comprises a molded structural plastic as a base and witha top coat of "soft touch" paint applied thereto.

While each of these three processes provide desirable finishing coversand other like products, "super soft" top cover manufacturing involvesrelatively complex production procedures generally requiring specialtooling for foaming the polyurethane and for the outer skin application.Furthermore, the aesthetic requirements of this process renders it themost costly of the three processes identified above. The "soft" topcover process is a time consuming and labor intensive method,particularly, since it requires the application of an adhesive to theskin and a thermoforming process to bond the components together. The"soft touch" top covers use a paint coating that is also labor intensiveand generally compares cost wise with the "super soft" process. In anyevent, the plastics components of the "super soft" and "soft" covers arenot from the same family of plastics materials so that separation of thedifferent plastics is necessary since different procedures and solventsare used for recycling different plastics, so that recycling isdifficult and expensive. This is also the case with the addition of the"soft touch" paint which introduces another incompatible material intothe life cycle management of a "soft touch" cover.

In view of the above considerations and others of the followingspecification, an object, feature and advantage of this invention is toprovide a new and improved process for producing a soft touch top coverof a plurality of different plastics materials but from the same familyof materials to form a quality part with good interior support anddesirable outer surface qualities which after completion of service lifeis readily and easily recyclable as a unitized part to provide improvedlife cycle management.

It is another feature, object and advantage to provide a new andimproved soft touch top cover that has a "soft to touch" outer skinextending over and integrated with a relatively hard and rigid or semirigid substrate providing a stabilizing base member.

Still another feature, object and advantage of this invention is toprovide a new and improved outer cover and method to produce a multilayer cover of a plurality of different plastics materials that are fromthe same family of recyclable plastics material which are fused togetherand which can be readily recycled.

Another feature, object and advantage of this invention is to make afinishing cover of two or more layers of separate and different plasticsmaterials from the same family of plastics which are compatible andrecyclable. This allows the finished cover to be recycled as a unitizedmember without the necessity of separating the plastics layers from oneanother and handling them as different materials. In this invention, oneof the cover components provides a relatively thick substrate forstructural rigidity while the outer component layer is a relatively thinouter sheet with a textured outer surface providing a "soft feel ortouch" sensation that one may experience when touching and rubbing theirhand across the outer surface thereof.

In the preferred embodiment of this invention, a pair of plasticsextruders are employed with a co-extrusion blow molding unit forproducing a co-extruded parison formed of two different materials of thesame plastics family. One extruder unit processes the base plasticsmaterial that is forced through a mandrel of a blow molding unit to formthe core of the parison while an associated satellite extruder processesthe plastics material also forced through the mandrel simultaneously toform the outer skin of the parison. When the parison has grown to asufficient size and the molding tools are being closed, low pressure airis injected into the parison so that the parison fully conforms to theconfiguration of the mold cavity. The closure force of the tools whenmolding the parison into a final shape, such as a finished cover of onefamily of plastics, causes the heat softened inner layers of the parisonto physically engage one another and fuse together. The outer layer orskin of the parison joins with the inner layers at the interfacetherewith because of miscibility of the two materials. When the part isbeing formed in the dies, an air passage may be molded into the coverproviding ducting for heat and air conditioning. The finished part whenremoved from the molds can be easily handled because of the structuralsupport of the core while the outer skin provides for the required "softfeel".

These and other features, objects and advantages of this invention willbecome more apparent from the following detail description and drawingin which:

DESCRIPTION OF THE DRAWINGS

FIG. 1 is diagrammatic side elevation view of plastics extruders andco-extrusion unit extruding a parison of plastics material into aforming mold, shown in open position;

FIG. 2 is a pictorial view of a portion of the forming mold of FIG. 1showing the mold in a closed position and the molding of a top cover;

FIG. 3 is a pictorial view of a portion of the formed part produced bythe mold operation of FIG. 1 and 2;

FIG. 4 is an enlargement of the circled portion of FIG. 3 showing themiscibility of the plastic layers forming the part of FIG. 3; and

FIG. 5 is a pictorial view showing the part in the form of an instrumentpanel top cover as installed in a vehicle.

DETAILED DESCRIPTION OF THE DRAWINGS

Turning now in greater detail to the drawings, there is shown in FIG. 1a co-extrusion blow molding unit 10 which is supplied with a quantity offirst thermoplastics material, such as high density polyethylene orpolypropylene each filled with suitable minerals such as Talc or Mica bymeans of a primary plastics extruder 12. The extruder has a plasticatingscrew 14 that is fed with the first thermoplastics 16 in granular orpowder form which is conventionally driven by an actuator 15. Theplasticating screw 14 is rotated by the actuator 15 and pulsated in theextruder housing to force heated plastics melt through the one-way valve20 of the screw 14 onto an inner accumulator 22 of the co-extrusion blowmolding unit 10. In the method or process of this invention this heatedplastics material forms the inner layer 24 of a parison 26 extrudedthrough the mandrel 28 of the unit.

In addition to the extruder 12, a second satellite plastics extruder 30has a plasticating screw 32 operatively mounted within the extruder thatis driven by an actuator 34. The extruder 30 and plasticating screw 32is supplied with a different kind of granular or powder thermoplasticsmaterial 36, such as polyethylene based polyolefin elastomer (POE) orpolypropylene based thermoplastic elastomer TPO which is of the samefamily of plastics as the first plastics material but has differentcharacteristics.

The second extruder unit 30 feeds heated plastics melt into an outerannular accumulator 40 of the accumulator head 42 of the co-extrusionblow molding unit 10. From the accumulator 40 the material in moltenstate is fed through the mandrel 28 in the end of the accumulator headto form the outer skin 31 of the parison 26. The parison isconventionally formed into a tubular shape so that it has sufficientmaterial and can be blown to correspond to the closed cavity 48 of themold tooling 50, 52, but shown in the open position in FIG. 1. The twomolds halves are operated by the power cylinders 54, 56 to move the moldhalves between open and closed positions. As the mold is closing,pressurized air is injected into the parison through air supplyinjectors 60. This air may be injected into a centralized region 64 ofthe parison as air is exhausted therefrom through exhaust tube 62appropriately sized or controlled to control the air pressure in thisarea. Accordingly, the parison conforms to the cavity of the mold, asshown in the sectional view in FIG. 2. With this blow molding, an airconducting passage or duct 66 extending transversely within the moldedpart here forming a top cover 68 is provided.

As shown best in FIGS. 3, 4 and 5, the molded top cover 68 has theinterior layers 70, 72 forming an integrated rigid substrate provided bythe inner layer 24 or wall of the parison forced and fused together bythe mold halves while the outer layer or skin 31 of the parison formsthe peripheral or outer layer 74 of the top cover.

In FIG. 3, the top cover 68 is shown substantially finished with theouter layer 74 providing the "soft feel" show surface of the top cover.

The relatively thin outer layer 74 interfaces as at 75 with the innerlayers of the top cover, and since the plastics are miscible, theycombine or join and securely bond together in this area.

In the event that different colors are employed, such a bright color forthe outer layer and a dark color for the inner layer, the layers will beclearly distinct from one another, such as shown in FIG. 4. However, inthe event that the layers are substantially of the same color, and withfused interfaces they will be difficult to discern from one another.

In FIG. 5, the molded top cover is installed in a vehicle as a cover foran instrument panel and is fastened to structure 84 therein by suitablefasteners 86. As shown in dashed lines, an air blower 88 is providedwhich has an output 89 operatively connected to the transverse crosschannel 90 formed by the blow molding operation of FIG. 2 to pumpstreams of air therethrough. With this construction, there is alsoimproved acoustical performance and reduced vibrational noises, such assqueaks and rattles between the panel and its adjacent structuresbecause of vibrating damping provided by the panel.

The substrate layers 70, 72 or base of the top cover is formed by theinterior layer of the parison and being of the first dense plastics hassubstantial rigidity or is at least semi-rigid so as to provide goodsupport for the outer cover. The outer cover preferably has lowdurometer hardness and has a "soft feel" characteristics as when aperson lightly touches and moves their hand across the outer peripheryof the instrument panel. This "soft feel" does not necessarily includedeformation of the top cover with or without memory or resilience butdoes include the tactile soft feeling of the cover when touched. Such"soft feel" is desirable for many applications, such as the top cover ofthe instrument panel as described, or other covered areas or interiorcomponents.

In this invention, recycling is enhanced since the instrument panelcover is a material of one family. More particularly, when the vehicleis being recycled, the panel can be removed from the interior of thevehicle and then shredded without the requirement of removing thefinishing cover from the backing layer or base as previously required inprior art instrument panel covers. Accordingly, the outer and innerlayers of the instrument panel can be cut into particles or granulizedand recycled and used as the substrate thermoplastics material 16 inFIG. 1 to be extuded as the inner layer 24 of the parison 26. The softfeel layer will be provided by material 36 as previously described. Therecycled plastics material can also be readily used to make othersuitable articles.

The core or substrate material 16 suitable for this invention may be ahigh density polyethylene such as "Marlex" produced by PhillipsPetroleum Co. or HDPE produced by Dow Chemical Co. Another suitablesubstrate material is a polypropylene such as "Escorene" or "Mytex"produced by Exxon.

The skin can be made from polyethylene based Polyolefin elastomer (POE)such as "ENGAGE" produced by Dow Chemical, or polypropylene basedthermoplastic elastomer TPO such as "Dexflex" from D & S or "Mytex" fromExxon.

While preferred embodiments and methods of the invention have been shownand described, other embodiments and methods will now become apparent tothose skilled in the art. Accordingly, this invention is not to belimited to that which is shown and described but by the followingclaims.

What is claimed is:
 1. A unitized soft feel all plastics cover forfinishing components of an automotive vehicle comprising a stiffenedsupport core of at least two relatively thicker inner and flattenedlayers of a recyclable first thermoplastics material disposed in aninterfacing top and bottom relationship and permanently bonded to oneanother at the interface thereof, and a flexible and relatively thinouter layer of a recyclable second thermoplastic material of the samefamily of materials as said first thermoplastic material and surroundingand in direct contact with the outermost surfaces of said support coreso as to become miscible and permanently bonded thereto at least at theinterface thereof, said outer layer having an outer surface providing asoft feel to the physical touch thereof, said inner and outer layersforming the entire cover which can be cut into particles for recyclingwithout separating said inner and outer layers from one another.
 2. Thesoft feel cover of claim 1 having a discrete air conducting passageformed between the relatively thick layers of the support core.
 3. Aunitized soft feel all plastics cover for finishing instrument panels ofautomotive vehicles comprising a rigid core of at least two relativelythicker inner layers of a first thermoplastic material of substantiallyconstant thickness disposed in a sandwiched top and bottom relationshipand permanently joined together at the common interface thereof, and aflexible and relatively thin cover layer of a second thermoplasticmaterial of the same family of materials as said first plastic materialand surrounding and in direct contact with the entire outermost surfacesof said core so as to become miscible and permanently and fully joinedthereto at the interface thereof, said permanently joined cover layerand inner layers forming the entire cover which can be granulized andrecycled.
 4. The soft feel cover of claim 3 having a discrete airconducting passage formed between the relatively thick layers of thesupport core.